Ok, well phase 1 of the installation is complete (functional, not beautiful) and now I'm preparing for phase 2. My question comes in that currently I am running 1 4ga ground and a 2 ga power wire, both directly to the battery. I was wondering if I should run a second 4ga wire to underneath the seat, run a second 4ga to the battery, or replace the 4ga with a 2ga. Currently the total wire length looks to be about 15'. I know I'm going to need additional grounding, I'm running 2 amps (111 x 4 RMS and 456 x 1 RMS, totaling 900w RMS). I'm running a 1.5 farad cap with this setup to stiffen everything nicely. The entire system will be running at 4 ohms, none of the amps are going to be bridged.

 

I think you are definitely covered in the power wire gauge department, as for that length of ground I cannot say either way if 2 gauge would help any ... are you still having some noise issues? Have you tried a ground inside 18" or so yet? Did not hear back whether it helped or if it was fixed from that "MSD" thread.

Fej

 

If you are running the ground from the amps back to the battery, it should be the same size and length as the power wire from the battery to the amps.
Many people will tell you not to run the ground back to the battery. It will not cause problems. It will only cost you more.
What those people just fail to understand is when the ground to the chassis they are doing the same thing. The only difference is most of them are using the stock ground wire from chassis to the battery which will be more constricting than the 2-guage you are thinking about using. Also, they don't realize the flow of electrons. Electricity flows like water. As long as your drain flow (ground) is not smaller than the facuet output (positive) you have no problems. The next arguement I hear is induced noise. I poise this question, why would a direct ground cable induce noise over short ground wire, then car chassis, then another short ground wire

 

I don't disagree with the science, I just know from installs in the past changing a 15' ground wire back to the battery to a 15" ground near the amp eliminated the alternator whine in his system (same gauge). Literally not a single other component or wire was changed or moved. Why it worked or how it worked I could not tell you, I just do KNOW it worked. Never had noise in a system I have installed for my rides, and never had a ground back to the battery so I stick with what I know works

Fej

 

fight fight fight

 

no way would I ever hit a lady

 

I'm just an amateur, but I would expect that the longer a cable is, the greater the opportunity for it to pick up noise and interference, right? BTW, if my first lady comment was the cause of all these "lady" jokes, then let me say:

 

I did some oscilliscope readings and the noise appears to be coming from the head unit. I haven't had the time to try the ground to the seat mount point yet, but I'm going to give it a try in about a week and a half (probably going to try a test line from the grounding lug I installed (to save the chat on this thread its not installed on metal, I'm just using it as a place to allow for further grounds to be mounted when I go for the big amp install)) I also picked up that capacitor off of ecklers to verify thats the problem (hell its a $20 thing that will either eliminate the MSD noise or at least decrease some of it). Speaking of, whats the best way to charge that 1.5 farad cap, hook it straight to the battery until the voltages equalize? The package said to use a light bulb, but I was curious about the current draw across such a small thing.

I know I'm running a smaller ground to the battery than the main power and its not the configuration I'd desire, its just what came in the JBL package and my own implementation of it (it came with about 15' 2ga power wire and 10' of ground wire with ring terminals already crimped plus some other junk). Bieng a fiberglass car I decided to run the grounds all the way back to the battery (also to reduce resistance). I was looking at the current handling capacities and it appears that it should be better to run 2 4ga wires that 1 2ga wire (reference).

The ground and power wires should be pretty safe against getting any noise in them, they're carrying a lot of power and will be on a capacitor before the amps.

 

Nothing but love around here, it overflows

G'luck VB I am sure you will get it figured out.

Fej

 

yes it is...thank you

I really love the audio forum. Everyone gets along and can take jokes well If I offended you Fej, I'm sorry. To Scott, I'm never sorry

My C5 is the only car I ever ran the ground to the battery. Running a 0-guage wire 15 feet compared to 15 inches is not cost effective. The only reason I did is the fiberglass car and cosmetic reasons. I have zero noise and I crank the system and rev high

One reason people have the dimming headlight problems are caused by a high powered system grounded to the car's chassis. Those people do a great job at using short thick wire to a unpainted surface. What they do not do is upgrade the battery's ground. So they have all this great stuff trying to get a ground through the factory's 8-guage (at best) ground wire. 99% of the installs I have done have the amps grounded to the chassis but I also run a new ground wire from the chassis (or engine block) to the battery. People usually do this when they see the 0-guage grounds.

Ice,
The light bulb can be used as a resistor for the cap. It can also be used as a fuse. I was amazed as how many passive crossovers used light bulbs as a fuse for tweeters.
I also forgot you were the one with the MSD problem...good luck with that. They are known for inducing noise, get out the Reynolds wrap

 

Me too Fej. I hope you know we pick on you and Scott just cause we love ya so much.

I can speak to the effectiveness of the "Big Three" upgrade on dimming headlights. When I got the first part of the install done last week, the headlights dimmed bad enough to almost go off on hard bass hits when I was at idle. We replaced the battery with a yellow top and the dimming was better but still significant. Did the "Big Three" and now the dimming is almost completely gone. So minimial that I will not do anything to fix it. Well worth the change. Installer charge $100 for the work, which seemed reasonable to me.

 

I ran my amp ground back to the battery, too.

It's 4 gauge, both ways, powering a JL Audio 500/5. I don't have any noise.

Something to consider... thanks to physics, electricity runs from the negative anode TO the positive anode, not the otherway around. It is REVERSE of common sense....

This is the exact reason why English cars used positive ground for so long.

as for a CAP, check out Alu-sonic. They make a cap that is just huge and works out to be a better unit for a better value. It's also faster acting... and easier to install.

 

Bogus...were you in the Navy? Maybe you know why I'm asking the question

 

cool, I'm remembering all of the lovely electronics info I used to know from the military slowly thanks to this section. One of the reasons I ran to the battery is that according to the Sound Advice guy the chassis was about the equivalent of a 4ga ground wire. Knowing the previous owner's installation to the seat mount caused a nice little rumble rumble when I moved around in the seat I figured I'd run it all the way back. If my math serves me right:
900w rms
--------- = 75A
12v DC
Bieng that according to that chart a 4ga cable is only meant for 60A I would actually be overloading the cable. Running 1 2ga would give me 94A of current capacity, but running 2 4ga wires would give me 120A. Bieng that I have a nice ground already running to the battery I think I might try to get the additional 10' of cable and spare 2 ring terminals to try this lil experiment out. 2 4ga wires are a HELL of a lot easier to run than another 2ga that car (I'm running them through the panel beneath the drivers door to hide them away). I am going to try to experiment with that seat mount idea with the other ground prior to that, I am curious as to its outcome. Both should work out nicely .

As for the cap I'm overdoing it with a 1.5 farad cap from some off-brand place. It matches my setup and gives me .6 farads more than I should ever need with this setup. Should be nice smooth power . Thanks for all of the input everyone!

 

no, but my nephew was.

 

The reason I asked is the Navy teaches that electrons flow from negitive to positive. The Army and Air Force (which I served) teaches that electrons flow from positive to negitive.

You are correct...but only if the amp is 100% efficient. We all know that isn't happening How efficient your amp all depends on the design (class and regulation) A class D amp will be much more efficient than a class A amp.

Not sure what chart you are refering to but I would think 4-guage would handle over 60 amps. I'm also not sure that two identical cables will double the current rating I would like to know that answer I'm too lazy to look it up and too dumb to remember from my electronic school days This I am sure of, you will be fine with 2-guage and 900 watts rms

 

That is correct. Now class lets all give Bogus a round of applause.


It doesnt matter if your ground is 15" or 15' ground is ground.

Both of my Alpines go to my seat bolt. No issue no noise. I have found over many installs that the only time I come up with noise is when my audio lines (AKA RCA's) get too close to my power lines (ground or postive), or bad ground.


I dont know the spec on these wires, but if this is true, than that is what you need to base you decision on.

 

pretty arrogant of the Army and AF to defy physics, don't you think?

 

No need for applause... just throw money.

 

Yup, the Navy teaches it negative to positive. I can vouch for that .